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package org.jruby.ext.fcntl;

import java.io.IOException;

import jnr.constants.Constant;
import jnr.constants.ConstantSet;
import org.jruby.Ruby;
import org.jruby.RubyFixnum;
import org.jruby.RubyModule;
import org.jruby.runtime.ThreadContext;
import org.jruby.runtime.load.Library;

import static org.jruby.api.Convert.asFixnum;
import static org.jruby.api.Define.defineModule;

/**
 * Populates all the constants for Fcntl from Constantine
 */
public class FcntlLibrary implements Library {
    // TODO: FD_CLOEXEC is mysterious and we are not sure how constantine should include this.
    // We did it here for now
    public static final int FD_CLOEXEC = 1;

    public void load(final Ruby runtime, boolean wrap) throws IOException {
        var context = runtime.getCurrentContext();
        var Fcntl = defineModule(context, "Fcntl").
                defineConstant(context, "FD_CLOEXEC", asFixnum(context, FD_CLOEXEC));

        loadConstantSet(context, Fcntl, "Fcntl");
        loadConstantSet(context, Fcntl, "OpenFlags");
    }

    /**
     * Define all constants from the named jnr-constants set which are defined on the current platform.
     *
     * @param module the module in which we want to define the constants
     * @param constantSetName the name of the constant set from which to get the constants
     */
    private static void loadConstantSet(ThreadContext context, RubyModule module, String constantSetName) {
        for (Constant c : ConstantSet.getConstantSet(constantSetName)) {
            if (c.defined() && Character.isUpperCase(c.name().charAt(0))) {
                module.defineConstant(context, c.name(), asFixnum(context, c.intValue()));
            }
        }
    }
}
